Clearly it is the case that there are some sole proprietor firms which provide entertainment services. While this is generally not the world's most lucrative market, we have no reason to suspect that it is intrinsically a worse business than the least sustainable sustainable enterprise.

There exists a class of specialized entertainment service provider. They are called "professional poker players" and their job is to fill seats at a poker table so that recreational players like myself can get into a poker game [+]. They are compensated irregularly for providing this service; incompetent professionals are swiftly driven from the market. An incidental portion of their compensation comes directly from casinos; a majority of it comes from people like me.

[+] Unlike some forms of gambling in Las Vegas, poker games are not immediately expandable at all margins. A casino with one dealer and three players for a full-ring game is sad. A casino with one dealer and six players is less sad; the game starts and the casino starts making a (relatively nominal) amount of money.

(The economics of poker are not attractive to a casino by comparison to the other games in the casino; it is mostly treated as a loss-leader to bring people seeking entertainment into an environment designed to extract all money in their wallet and then some.)